1. Field of the Invention
This invention relates to new sialic acid derivatives and more specifically to sialic acid derivatives having active ester groups in the molecules, biochemical half life extenders of biologically active substances, sialic acid derivatives bonding these sialic acid derivatives with amino compounds, and intermediate compounds used for synthesis of the sialic acid derivatives.
2. Related Art Statement
Neuraminic acid derivatives including N-acetylneuraminic acid, that is, sialic acid derivatives, are known to exist widely in the animal world or on the cell surface of several bacteria such as sialo complexes, more specifically, glycoproteins, glycolipids, oligosaccharides, and polysaccharides.
The above-mentioned sialic acid derivatives are compounds which have recently become highly valuable in medical and pharmaceutical fields, in the treatment of nervous functions, cancer, inflammation, immunity, virus infection, differentiation, and hormone receptor, and are attractng keen attention as particularly active molecules located on the cell surface.
Various theories have been set forth about the role played by sialic acid derivatives in the aforementioned sialo complex, but there are many things that have not yet been clarified, and are still a matter of conjecture.
The inventors have studied sialic acid derivatives for many years and succeeded in synthesizing sialic acid derivatives which exhibit conspicuous biological activity (Japanese Patent Application No.62-295641).
Recently, the inventors discovered a new sialic acid derivative that exhibits conspicuous biological activity and in the subject matter of this invention.